Data input circuit and semiconductor device utilizing data input circuit

ABSTRACT

A data input circuit converts input serial data to n-bit parallel data, and outputs the n-bit parallel data by following an address signal. The data input circuit includes a data shifting unit including a plurality of columns, and sequentially shifting the input serial data through the plurality of columns; and a selection unit selecting a column among the plurality of columns as an input column by following the address signal, wherein the input serial data is inputted to the data shifting unit through the input column. Thus, the data input device can speed up its processing speed with a simplified circuit structure whose circuit size is reduced.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a data input circuit and asemiconductor device utilizing the data input circuit. The presentinvention more particularly relates to a data input circuit receivingserial data synchronously to a clock, and converting the serial data toparallel data, and a semiconductor device utilizing the data inputcircuit.

2. Description of the Related Art

Some semiconductor devices include an input circuit converting serialdata supplied from outside the semiconductor devices to parallel data,and outputting the parallel data to a data bus by following an addresssignal. The input circuit creates a plurality of address signals from asingle address signal supplied in accordance with a command signal, andoutputs the parallel data to the data bus by following the plurality ofaddress signals.

FIG. 1 is a diagram showing a configuration of a conventional inputcircuit. An input circuit 100 includes an input buffer 110, a shiftregister 120 (a data-acquiring buffer) and a data switch unit 130. Thedata switch unit 130 includes switches 131 through 134. Additionally,FIGS. 2A and 2B are diagrams showing signal processes performed by theinput circuit 100. It should be noted that FIGS. 1, 2A and 2B show acase in which data is supplied to the input circuit 100 by a DDR (DoubleData Rate) method supplying the data with a frequency twice as higherthan that of an external clock, for instance.

An address signal A2 is initially supplied to the input circuit 100 witha data-write command as shown in FIG. 2A. The address signal A2 is oneof address signals A0, A1, A2 and A3 expressed by a combination of theleast two significant bits (Y1, Y0) of an address. Additionally, theaddress signal A2 supplied with the data-write command to the inputcircuit 100 indicates that input data is supplied to the input circuit100 in order of data A2, data A3, data A0 and data A1 continuously afterthe address signal A2 and the data-write command have been supplied. Tobe concrete, the data A2, A3, A0 and A1 is supplied through the inputbuffer 110 to the shift register 120 in the order of the data A2, A3, A0and A1 by following a frequency of an internal clock CLK1. The shiftregister 120 shifts data supplied thereto one by one as shown in FIG.2B. For example, if an address signal supplied with the data-writecommand to the input circuit 100 is the address signal A2, the shiftregister 120 stores the data A2, A3, A0 and A1 respectively in areas N0,N1, N2 and N3 of the shift register 120.

The areas N0, N1, N2 and N3 of the shift register 120 are respectivelyconnected to the switches 131, 132, 133 and 134 included in the dataswitch unit 130. The switches 131 through 134 are connected to databuses A0 through A3. The input circuit 100 outputs input data to a databus corresponding to a supplied address signal by controlling theswitches 131 through 134 by following the supplied address signal. Forexample, in the case in which an address signal supplied with thedata-write command to the input circuit 100 is the address signal A2,the areas N0, N1, N2 and N3 are respectively connected with the databuses A2, A3, A0 and A1 as shown in FIG. 2B. As described above, theinput circuit 100 creates a group of four address signals, each addresssignal corresponding to a combination of the least two significant bitsof an address, automatically recognizes an order of four input data, andoutputs the four input data to their corresponding data buses. Such anoperation is called a 4N operation.

As described above, the input circuit 100 needs to include a largenumber of switches in the data switch unit 130. The data switch unit 130needs to have (2^(n))² switches in a case of creating a group of 2^(n)address signals, each address signal corresponding to a combination ofthe least “n” significant bits of an address, automatically recognizingan order of 2^(n) input data, and outputting the 2^(n) input data totheir corresponding data buses. For instance, in the 4N operation, thedata switch unit 130 needs to have 4² switches. Consequently, a circuitarea of the input circuit 100 increases by a larger amount as the numberof input data increases. Additionally, the configuration of the inputcircuit 100 becomes more complicated.

FIG. 3 is a diagram showing a configuration of another conventionalinput circuit. An input circuit 200 shown in FIG. 3 includes the inputbuffer 110, data-acquiring buffers 140 (N0) through 143 (N3), and anaddress counter 150. Additionally, FIGS. 4A, 4B and 4C are diagramsshowing signal processes performed by the input circuit 200. The inputcircuit 200 achieves the 4N operation by controlling a data-acquiringclock supplied to the data-acquiring buffers 140 through 143 that areprovided for the input data A0 through A3.

The address signal A2 is initially supplied to the input circuit 200with the data-write command as shown in FIG. 4A. The address counter 150generates data-acquiring clocks 1 through 4 by following the addresssignal A2 as shown in FIG. 4B, and supplies the data-acquiring clocks tothe data-acquiring buffers 140 through 143. To be concrete, thedata-acquiring clocks 1, 2, 3 and 4 are respectively supplied to thedata-acquiring buffers 140, 141, 142 and 143. The data-acquiring buffers140 through 143 obtain the input data A0 through A3 respectively atrising edges of the data-acquiring clocks 1 through 4 as shown in FIG.4C. Subsequently, the data-acquiring buffers 140 through 143 outputsobtained input data, for example, the input data A0 through A3respectively to the data buses A1 through A3.

The input circuit 200 shown in FIG. 3 needs to generate thedata-acquiring clocks at the highest frequency possible. However, sincea logical circuit such as the address counter 150 must generate thedata-acquiring clocks, speed up of processes executed by the inputcircuit 200 is hard.

SUMMARY OF THE INVENTION

Accordingly, it is a general object of the present invention to providea data input circuit and a semiconductor device utilizing the data inputcircuit. A more particular object of the present invention is to providea data input device speeding up its processing speed with a simplifiedcircuit structure reducing a circuit size, and a semiconductor deviceutilizing the data input device, in which the disadvantages describedabove are eliminated.

The above-described object of the present invention is achieved by adata input circuit converting input serial data to n-bit parallel data,and outputting the n-bit parallel data by following an address signal,the data input circuit including a data shifting unit including aplurality of columns, and sequentially shifting the input serial datathrough the plurality of columns; and a selection unit selecting acolumn among the plurality of columns as an input column by followingthe address signal, wherein the input serial data is inputted to thedata shifting unit through the input column.

The selection unit selects the column to input the input serial data tothe data shifting unit. Subsequently, the data shifting unit obtains theinput serial data, and shifts the input serial data so that the inputserial data stored in each column of the data shifting unit can beoutputted to its corresponding destination.

Thus, the data input device can speed up its processing speed with asimplified circuit structure reducing a circuit size.

Other objects, features and advantages of the present invention willbecome more apparent from the following detailed description when readin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a configuration of a conventional inputcircuit;

FIGS. 2A and 2B are diagrams showing signal processes performed by theconventional input circuit;

FIG. 3 is a diagram showing a configuration of another conventionalinput circuit;

FIGS. 4A, 4B and 4C are diagrams showing signal processes performed bythe conventional input circuit shown in FIG. 3;

FIG. 5 is a diagram showing a configuration of an input circuitaccording to a first embodiment of the present invention;

FIGS. 6A and 6B are diagrams showing signal processes performed by theinput circuit according to the first embodiment;

FIG. 7 is a diagram showing a configuration of a shift register,according to the first embodiment;

FIG. 8 is a diagram showing a configuration of the input circuitaccording to a second embodiment of the present invention;

FIGS. 9A and 9B are diagrams showing signal processes performed by theinput circuit according to the second embodiment;

FIG. 10 is a diagram showing a configuration of the shift register,according to the second embodiment; and

FIG. 11 is a block diagram showing a configuration of a semiconductordevice utilizing the input circuit according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A description will now be given of preferred embodiments of the presentinvention, with reference to the accompanying drawings.

FIG. 5 is a diagram showing a configuration of an input circuit 1according to a first embodiment of the present invention. The inputcircuit 1 shown in FIG. 5 includes an input buffer 10, an input-pointselector (a decoder) 12, a shift register (a data-acquiring buffer) 14,inverters 16 through 20, and NAND gates 21 through 23. The input circuit1 generates a plurality of address signals from a single address signalsupplied in accordance with a command signal, converts serial datasupplied from outside the input circuit 1 to parallel data, and outputsthe parallel data to a data bus by following the plurality of addresssignals.

A description will now be given of a case in which the input circuit 1creates a group of four address signals, for example, address signals A0through A3, each address signal corresponding to a combination of theleast two significant bits of an address, automatically recognizes anorder of four input data, and outputs the four input data to theircorresponding data buses A0 through A3. The shift register 14 includesseven columns that are N3, N2, N1, N0, N3′, N2′ and N1′, and shiftsinput data from the column N3 toward the column N1′. If the inputcircuit 1 uses a group of 2^(n) address signals in which a number “n” isa natural number, the shift register 14 includes 2^(n+1)−1 columns. Theinput-point selector 12 controls a data input point of the shiftregister 14 by following an address signal inputted thereto. Forexample, the input-point selector 12 selects the column N1 as the datainput point of the shift register 14 in a case in which the addresssignal A2 is supplied to the input circuit 1 with a data-write command.The columns N3 and N3′ of the shift register 14 are connected to theNAND gate 21 whose output terminal is connected to the data bus A3through the inverter 16. Similarly, the columns N2 and N2′ of the shiftregister 14 are connected to the NAND gate 22 whose output terminal isconnected to the data bus A2 through the inverter 17. The columns N1 andN1′ of the shift register 14 are connected to the NAND gate 23 whoseoutput terminal is connected to the data bus A1 through the inverter 18.Additionally, the column N0 of the shift register 14 is connected to thedata bus A0 through the inverters 20 and 19.

FIGS. 6A and 6B are diagrams showing signal processes performed by theinput circuit 1, according to the first embodiment. The address signalA2 is initially supplied with the data-write command to the inputcircuit 1 as shown in FIG. 6A. The address signal A2 is one of theaddress signals A0 through A3 expressed by a combination of the leasttwo significant bits (Y1, Y0) of an address. The address signal A2supplied with the data-write command indicates that the input data issupplied to the input circuit 1 in order of the input data A2, A3, A0and A1 after the address signal A2 is supplied thereto. If the addresssignal A3 is supplied with the data-write command to the input circuit1, the input data is supplied to the input circuit 1 in order of theinput data A3, A0, A1 and A2 after the address signal A3 is suppliedthereto. The input-point selector 12 selects the column N1 as a datainput point of the shift register 14 by following the supplied addresssignal A2 as shown in FIG. 6A. Subsequently, the input data is suppliedto the shift register 14 through the input buffer 10 by following afrequency of an internal clock CLK1 in the order of the input data A2,A3, A0 and A1. Since the input-point selector 12 selects the column N1of the shift register 14 as the data input point, the input datasupplied from the input buffer 10 is inputted to the column N1continuously in the order of the input data A2, A3, A0 and A1. As aresult, the columns N1, N0, N3′ and N2′ store respectively the inputdata A1, A0, A3 and A2 as shown in FIG. 6B. The columns N1′, N2 and N3not storing the input data store a predetermined value, for example, ahigh-level signal or value as shown in FIG. 6B.

The input data A0 stored in the column N0 of the shift register 14 isoutputted to the data bus A0 through the inverters 20 and 19. The inputdata A1 stored in the column N1 of the shift register 14 and a valuestored in the column N1′ of the shifter register 14 are supplied to theNAND gate 23, whose output is outputted to the data bus A1 through theinverter 18. Similarly, the input data A2 stored in the column N2′ ofthe shift register 14 and a value stored in the column N2 of the shifterregister 14 are supplied to the NAND gate 22, whose output is outputtedto the data bus A2 through the inverter 17. The input data A3 stored inthe column N3′ of the shift register 14 and a value stored in the columnN3 of the shifter register 14 are supplied to the NAND gate 21, whoseoutput is outputted to the data bus A3 through the inverter 16. Forinstance, the values stored in the columns N1′, N2 and N3 are high-levelsignals, the input data A1 stored in the column N1, the input data A2stored in the column N2′ and the input data A3 stored in the column N3′are outputted to the data bus A1, A2 and A3 respectively.

FIG. 7 is a diagram showing a configuration of the shift register 14,according to the first embodiment. The shift register 14 shown in FIG. 7includes switches SW0 through SW3, flip-flops FF0 through FF3 and FF1′through FF3′, inverters 30 trough 33, and NOR gates 34 through 37. Theinput-point selector 12 outputs a signal selecting the column N1 of theshift register 14 to the shift register 14 by following the addresssignal A2 after receiving the address signal A2 and the data-writecommand as shown in FIG. 6A. To be concrete, the input-point selector 12outputs a high-level signal from its output terminal N(A2) to the switchSW2 of the shift register 14, and low-level signals from the otherterminals N(A0), N(A1) and N(A3) respectively to the switches SW0, SW1and SW3. The switch SW2 connects to a side “b” after receiving thehigh-level signal from the output terminal N(A2) of the input-pointselector 12. Each of the switches SW1 and SW3 connects to a side “a”after receiving the low-level signal respectively from the outputterminals N(A1) and N(A3) of the input-point selector 12. Additionally,the switch SW0 becomes disconnected after receiving the low-level signalfrom the output terminal N(A0) of the input-point selector 12.

Consequently, the input data A2, A3, A0 and A1 is inputted continuouslyto the flip-flop FF1 of the shift register 14 through the switch SW2connected to the side “b”, and is shifted one after another toward theflip-flop FF1′. Because of shifting the input data, the shift register14 stores the input data A1, A0, A3 and A2 respectively in theflip-flops FF1, FF0, FF3′ and FF2′. Additionally, the shift register 14is configured so as to supply a SET signal to the flip-flops FF3, FF2and FF1′, which do not store the input data. When a high-level SETsignal is supplied, a flip-flop outputs a high-level signal from itsoutput terminal Q.

According to the first embodiment, the input circuit 1 can select a datainput point (a column) of the shift register 14 by following an addresssignal by use of the input-point selector 12, thereby enablingconversion of supplied serial data to parallel data and output of theparallel data to its corresponding data bus or the like. Additionally,the input circuit 1 includes 2n−1 columns in the shift register 14 inorder to generate n-bit parallel data and selecting the data input pointamong the 2n−1 columns, thereby enabling conversion of supplied serialdata to the n-bit parallel data and output of the n-bit parallel data toits corresponding data bus or the like. In the case of including the2n−1 columns in the shift register 14, columns not storing the suppliedserial data are also included in the shift register 14. Thus, the inputcircuit 1 can obtain the n-bit parallel data by executing a logicalarithmetic operation on a combination of data outputted from the columnsnot storing the supplied serial data and from the columns storing thesupplied serial data.

FIG. 8 is a diagram showing a configuration of an input circuit 2according to a second embodiment of the present invention. The inputcircuit 2 shown in FIG. 8 includes the input buffer 10, the input-pointselector 12, a shift register 40, and inverters 42 through 49. A unitshown in FIG. 8 having the same unit number as a unit shown in FIG. 5 isequivalent to the unit shown in FIG. 5. The shift register 40 includesfour columns N3, N2, N1 and N0, and shifts input data in a directionfrom the column N3 to the column N0. Additionally, the shift register 40is provided with a feedback loop so that input data shifted to thecolumn N0 is fed back to the column N3 at the next shift. The shiftregister 40 needs to have 2^(n) columns in which a number “n” is anatural number if a group of 2^(n) address signals is provided thereto.The input-point selector 12 controls a data input point of the shiftregister 40 by following an address signal inputted thereto similarly tothe shift register 14 described in the first embodiment. The column N3of the shift register 40 is connected to the data bus A3 through theinverters 46 and 42. Similarly, the column N2 of the shift register 40is connected to the data bus A2 through the inverters 47 and 43. Thecolumn N1 of the shift register 40 is connected to the data bus A1through the inverters 48 and 44. The column N0 of the shift register 40is connected to the data bus A0 through the inverters 49 and 45. Theshift register 40 thus outputs input data stored in the columns N0through N3 to the data buses A0 through A3 respectively.

FIGS. 9A and 9B are diagrams showing signal processes performed by theinput circuit 2, according to the second embodiment. The address signalA2 and the data-write command are supplied to the input circuit 2 asshown in FIG. 9A. The input-point selector 12 selects the column N1 as adata input point of the shift register 40 as shown in FIG. 9A.Subsequently, the input data is supplied to the shift register 40through the input buffer 10 by following the frequency of the internalclock CLK1 in order of the input data A2, A3, A0 and A1. Since theinput-point selector 12 selects the column N1 of the shift register 40as the data input point of the shift register 40, the input data A2, A3,A0 and A1 is continuously inputted to the shift register 40 from thecolumn N1. The input data A2 initially enters the column N1, and isstored in the column N1. At the next step, the input data A3 enters thecolumn N1, and is stored in the column N1. Meanwhile, the input data A2is shifted to the column N0, and is stored in the column N0.Subsequently, at the time the input data A0 is entering the column N1,the input data A3 is shifted to the column N0 as well as the input dataA2 is fed back to the column N3. Thus, after the input data A2, A3, A0and A1 is inputted from the column N1 to the shift register 40 one byone, the shift register 40 stores the input data A3, A2, A1 and A0respectively in the columns N3, N2, N1 and N0. Subsequently, the inputdata A3, A2, A1 and A0 stored respectively in the columns N3, N2, N1 andN0 of the shift register 40 is outputted respectively to the data busesA3, A2, A1 and A0 through two inverters.

FIG. 10 is a diagram showing a configuration of the shift register 40,according to the second embodiment. The shift register 40 shown in FIG.10 includes switches SW0 through SW3, and flip-flops FF0 through FF3.After receiving the address signal A2 with the data-write command asshown in FIG. 9A, the input-point selector 12 outputs a control signalto set the data input point of the shift register 40 to the column N1 byfollowing the address signal A2. To be concrete, the input-pointselector 12 outputs a high-level signal (HIGH) from its output terminalN(A2), and low-level signals (LOW) from its output terminals N(A0),N(A1) and N(A3), as shown in FIG. 9A. Since the switch SW2 is connectedto the output terminal N(A2) of the input-point selector 12, andreceives the high-level signal therefrom, the switch SW2 is connected toa side “b”. Additionally, the switches SW0, SW1 and SW3 are respectivelyconnected to the output terminals N(A0), N(A1) and N(A3) of theinput-point selector 12, and receive the low-level signal, the switchesSW0, SW1 and SW3 are connected to their sides “a”.

Accordingly, the input data supplied from the input buffer 10 isinputted to the flip-flop FF1 through the switch SW2 connected to theside “b”. Subsequently, the input data A2, A3, A0 and A1 inputted to theshift register 40 from the flip-flop FF1 is shifted in order through theswitches SW1, SW0 and SW3, which are connected to the sides “a”. Inputdata stored in the flip-flop FF0 is shifted when new input data isinputted to the flip-flop FF1.

As described above, the shift register 40 can select a data input pointby following an address signal supplied with the data-write command, andcan output supplied input data to their corresponding data buses.Additionally, the input circuit 2 according to the second embodimentstores input data in all the flip-flops provided in the shift register40, and thus does not have to provide a SET signal necessary in the fistembodiment to the shift register 40, thereby achieving objects of thepresent invention with a simpler circuit structure.

Additionally, the input circuit 2 includes a feed-back loop in the shiftregister 40, and thus does not need to include no more than n columns inthe shift register 40 for generating n-bit parallel data.

According to the first and second embodiments, the shift registers 14and 40 include a plurality of switches and flip-flops, thereby enablinginput of serial data to the shift registers 14 and 40 through theplurality of flip-flops.

FIG. 11 is a block diagram showing a configuration of a semiconductordevice 3 utilizing the input circuit 1 or 2 according to the presentinvention. The semiconductor device 3 shown in FIG. 11 is a SDRAM(Synchronous Dynamic Random Access Memory) utilizing a delayed-writemethod and the input circuit 1 or 2 according to the present invention.Data inputted to the semiconductor device 3 is supplied to aserial-parallel converter 52 through a buffer/register 50, theserial-parallel converter 52 corresponding to the input circuit 1 or 2.The serial-parallel converter 52 can generate a plurality of addresssignals from a single address signal supplied in accordance with acommand signal, can convert serial data to parallel data, and can outputthe parallel data to a common data bus. It should be noted that thesingle address signal necessary for processes performed by the presentinvention is supplied to the serial-parallel converter 52.

Thus, by applying the input circuit 1 or 2 to the semiconductor device3, the semiconductor device 3 can reduce its circuit size, and canconvert supplied serial data to parallel data speedily as well as canoutput the parallel data to a data bus.

As describe above, the present invention provides a method of convertingserial data to parallel data by inputting the serial data to a datashifting method from a column of the data shifting method determined byuse of an address signal, and outputting the parallel data to itscorresponding data bus. Therefore, the present invention can provide adata input device speeding up its processing speed with a simplifiedcircuit structure whose circuit size is reduced, and a semiconductordevice utilizing the data input device.

The above description is provided in order to enable any person skilledin the art to make and use the invention and sets forth the best modecontemplated by the inventors of carrying out the invention.

The present invention is not limited to the specially disclosedembodiments and variations, and modifications may be made withoutdeparting from the scope and spirit of the invention.

The present application is based on Japanese Priority Application No.2000-030803, filed on Feb. 8, 2000, the entire contents of which arehereby incorporated by reference.

1. A data input circuit converting input serial data to n-bit paralleldata, and outputting the n-bit parallel data by following an addresssignal, said data input circuit comprising: a data shifting unitincluding a plurality of columns, and sequentially shifting the inputserial data through the plurality of columns; and a selection unitselecting a column among the plurality of columns as an input column byfollowing the address signal, wherein the input serial data is inputtedto said data shifting unit through the input column.
 2. The data inputcircuit as claimed in claim 1, wherein said data shifting unit includes2n−1 columns, and said selection unit selects the input column throughwhich the input serial data is inputted to said data shifting unit. 3.The data input circuit as claimed in claim 2, wherein said data shiftingunit executes a logical arithmetic operation on a combination of outputsof n columns storing the input serial data and outputs of n−1 columnsnot storing the input serial data, thereby converting the input serialdata to the n-bit parallel data following the address signal.
 4. Thedata input circuit as claimed in claim 1 wherein: said data shiftingunit includes n columns, and a feed-back function feeding the inputserial data stored in a n′th column of said data shifting unit back to afirst column of said data shifting unit; and said selection unit selectsthe input column by following the address signal so as to input theinput serial data to said data shifting unit.
 5. The data input circuitas claimed in claim 4, wherein said data shifting unit converts theinput serial data to the n-bit parallel data following the addresssignal by outputting the input serial data from the n columns storingthe input serial data.
 6. The data input circuit as claimed in claim 1wherein, said input serial data is inputted by n bits to said datashifting unit, and a destination of each bit is determined by theaddress signal.
 7. The data input circuit as claimed in claim 1,wherein: said data shifting unit includes a plurality of data storageunits as the plurality of columns, and a plurality of switching unitscontrolled by said selection unit, said plurality of data storage unitsstoring the input serial data; and said selection unit selects a datastorage unit as the input column among the plurality of data storageunits by controlling the plurality of switching units.
 8. Asemiconductor device including a data input circuit converting inputserial data to n-bit parallel data, and outputting the n-bit paralleldata by following an address signal, said semiconductor devicecomprising: a data shifting unit including a plurality of columns, andsequentially shifting the input serial data through the plurality ofcolumns; and a selection unit selecting a column among the plurality ofcolumns as an input column by following the address signal, wherein theinput serial data is inputted to said data shifting unit through theinput column.
 9. The Semiconductor device as claimed in claim 8,wherein: said data shifting unit includes a plurality of data storageunits as the plurality of columns, and a plurality of switching unitscontrolled by said selection unit, said plurality of data storage unitsstoring the input serial data; and said selection unit selects a datastorage unit as the input column among the plurality of data storageunits by controlling the plurality of switching units.
 10. A method ofconverting input serial data to n-bit parallel data, and outputting then-bit parallel data by following an address signal, said methodcomprising the steps of: selecting a column among a plurality of columnsof a data shifting unit as an input column by following the addresssignal; inputting the input serial data to said data shifting unitthrough the input column; and shifting the input serial datasequentially through the plurality of columns.